uboot

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config.mk

sinclude $(ARCH)_config.mk ；arm结构关系规则

sinclude cpu/$(CPU)/config.mk ；CPU特定规则

sinclude cpu/$(CPU)/$(SOC)/config.mk ；SOC特定规则

sinclude board/$(VENDOR)/$(BOARD)/config.mk ；BOARD特定规则

定义了编译器类型、编译器命令

$(ARCH)_config.mk

PLATFORM_CPPFLAGS += -DCONFIG_ARM -D__ARM__

mkconfig

创建include/config.mk,创建include/config.h

include/config.mk

定义ARCH=arm、CPU=s3c64xx、BOARD=smdk6410、VENDOR=samsung、SOC=s3c6410

include/config.h

定义flash,ram等，包含预定义文件include/configs/smdk6410.h

include/configs/smdk6410.h

预定义板级参数

#define CONFIG_NAND

board/$(VENDOR)/$(BOARD)/u-boot.lds

连接方式，定义__u_boot_cmd_start,__u_boot_cmd_end;__bss_start,_end

board/$(VENDOR)/$(BOARD)/config.mk

定义TEXT_BASE=0xC7E00000

cpu/$(CPU)/config.mk

PLATFORM_RELFLAGS += -fno-strict-aliasing -fno-common -ffixed-r8 -msoft-float

PLATFORM_CPPFLAGS += -march=armv5t

PLATFORM_RELFLAGS +=$(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,))

cpu/$(CPU)/start.S

#include <config.h> #include <version.h> #include <reg.h>

_start:

b reset

reset:

set the cpu to SVC32 mode

cpu_init_crit:

flush v4 I/D caches

disable MMU stuff and caches

Peri port setup

bl lowlevel_init

判断是否在RAM中执行（是：fater_copy）

bl copy_from_nand

after_copy:

enable_mmu:

copy_from_nand:

bl copy_uboot_to_ram（c）

board/$(VENDOR)/$(BOARD)/lowlevel_init.S

lowlevel_init:

mov r12,lr

disable watchdog,

external interrupt pending clear,

disable all interrupts(VIC0 and VIC1)

set all interrupts as IRQ,

pending interrupt clear

init system clock,

bl system_clock_init

for UART

bl uart_asm_init

KKKK

bl nand_asm_init

bl mem_ctrl_asm_init

if(sleep mode wake-up) wakeup_reset

KKKK

mov lr,r12

mov pc,lr

cpu/$(CPU)/$(SOC)/config.mk

cpu/$(CPU)/$(SOC)/cpu_init.S

mem_ctrl_asm_init: